Glide sensors are employed to analyze mechanical surfaces, and specifically are employed to analyze the surfaces of rigid magnetic recording disks. Such disks are utilized in magnetic storage disk drives, which comprise magnetic transducers supported on air bearing sliders in close proximity to relatively moving magnetic recording disks. The recording surface of the rigid magnetic recording disks are typically coated with a layer of magnetic material applied by sputtering.
Coated disks must be free of asperities to assure long term reliability and data integrity at the transducer to disk interface, since asperities can lead to undesirable slider-disk contact.
In order to increase disk drive data capacity without increasing the size of the drives, the transducers are of ever decreasing dimensions and the tracks of the disks are of ever decreasing widths, so that the magnetic fields are also of ever decreasing amplitudes. Thus, a magnetic transducer must be in even closer proximity to the disk recording surface to maximize its efficiency and sensitivity to read and write data.
The progressive reduction in slider flying height to bring the magnetic transducer into closer proximity with the recording surface of the disk requires a concomitant decrease in the asperity height (roughness) on the surface of the recording surface of the disk.
The process of detecting and rejecting disks with asperities is called a glide test. The glide sensor typically comprises a glide slider which is flown over the recording surface of the disk at a height equal to or below the desired magnetic transducer fly height. The slider is provided with a contact sensor which is bonded to an upper surface facing away from the recording surface. Piezoelectric sensors are typically used as the contact sensors because they generate an electric charge in response to internal stress. As the slider experiences rigid body displacement and flexural deformation, the bonded sensor responds by generating a charge signal which may be monitored. The incorporated '207 patent describes such a glide sensor.
Critical to the performance of the glide sensor is the ability to maintain a tightly controlled flying height and flying attitude (roll and pitch) of the glide slider to be able to make contact with disk asperities in a predictable manner.
The data sliders the modern format is called "Pico" (1.25 mm long by 1.00 mm wide and 0.3 mm thick), and future data sliders will be even smaller. Since the size of the slider air bearing surface determines the response of the slider flying over the disk surface, the glide slider needs to be of similar size in order to mimic the response of the data slider to the disk topology variation to detect asperities effectively.
A problem in using the Pico format for a glide slider is the increased sensitivity of flying height and flying attitude to the suspension static stiffnesses. If the static stiffness of the suspension is high, residual moments from the suspension that holds the slider above the disk surface tend to pitch or roll the slider out of an optimal flying attitude necessary for glide testing. Another problem is that the discrete wires used to connect the glide sensor to an output tend to add additional random moments that can significantly affect the glide slider attitude and flying height. This is because discrete wires usually have large positional variations due to assembly processes.
Thus, what is needed is a suspension for glide sensors which reduces static stiffness and avoids random moments, while providing electrical connections between the glide sensor and an output.